An updated radiocarbon dating technique has thrown our conceptions of when Neanderthals died out into question. A new paper in PNAS is suggesting that Neanderthals disappeared considerably earlier than previously thought — a resetting of the anthropological clock that calls into question whether our human ancestors interacted and interbred with the now-extinct species. But as the limited nature of the study suggests, we might want to hold off for bit before we re-write the history books.

For the past 20 years, anthropologists have assumed that the Neanderthals made their final stand in the northern part of the Iberian peninsula (the west coast of Spain) — a time when humans occupied the same space.

But now, an international study involving researchers from the Spanish National Distance Education University (UNED), Oxford University, Australia National University, and many other institutions, is claiming that this is highly improbable — that there's a slim chance Neanderthals were still alive in this region 30,000 years ago.

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Ultrafiltration protocol

According to co-author Jesús F. Jordá, a researcher at the Department of Prehistory and Archaeology of the UNED, the Neanderthals disappeared from Iberia no earlier than 45,000 years ago. And in fact, 50,000 years ago is the most plausible date. If the researchers are right, it means that humans and Neanderthals never interacted in this part of Europe, or if they did, it would have been for a short period of time (about 3,000 to 4,000 years).

The team reached this conclusion by applying a new radiocarbon dating method — one that utilizes an ultrafiltration protocol. It's a new technique that purifies the collagen of the bone samples, including the removal of unwanted contaminent molecules like amino acids.

"The problem with radiocarbon dating alone is that it does not provide reliable dates older than 50,000 years" explained Jordá through a statement. Contamination is another problem; older samples collect more residues, leading to incorrect analysis.

And with the new technique came new date ranges — changes that are altering our conceptions of the Neanderthal story.

Limited data

But before the history books get re-written, it's important to note that the team's samples were quite limited. The research team analyzed 215 fossil bones from 11 Iberian sites. But in the end, they were only able to identify 27 specimens, with only six of them producing a useable date. The problem was that the other samples contained insufficient collagen.

In addition to small sample size, the new technique may have resulted in a selection effect in which only older samples were isolated and dated.

Moreover, this research will have to be reconciled against other evidence in support of the idea that Neanderthals and humans crossed paths and interbred. While it's now clear that Neanderthals and humans may not have made contact in Iberia, anthropologists are still fairly certain that the two species did interact at other locations, and at other times.

A study from 2011, for example, suggested that modern humans were living in Italy and the UK as far back as 41,000 to 45,000 years ago. Other studies suggest that the Neanderthals hung on until 28,000 years ago — thus prolonging the potential "overlap" time with humans.

And not only that, there's the genetics to consider. There's enough evidence from DNA studies to suggest that interbreeding occurred between humans and Neanderthals (some 1 to 4 percent of Neanderthal DNA is present in modern humans). That said, it's quite possible that this mixing happened much longer ago, as much as 80,000 to 90,000 years ago in the eastern Mediterranean and Middle Eastern regions (what's referred to as the Levant Region).